As the use of computers becomes more ubiquitous for a large variety of tasks, the need to exchange information between computers also increases. As a result, networks for interconnecting computers, to allow such exchange of information, continue to grow. This growth occurs not only in the number of networks, but also in their size, as evidenced by the expanding use of local area networks (LANs), wide area networks (WANs), enterprise-wide networks (which might include several WANs) and, ultimately, world-wide networks, such as the internet.
To ensure reliable communications between computers, the networks themselves must be regularly managed. In general, the management of a network involves continued monitoring of the operating state of components which form the network, controlling those components to provide optimal performance under varying conditions, and troubleshooting sources of problem on the network. To this end, various operating models have been proposed for network management. In the operation of these models, information pertaining to the performance of components in the network is obtained, for example by management agents running on those components, and provided to a management process via an established protocol. For example, the SNMP (simple network management protocol) was developed for networks which operate on the basis of the internet protocol (IP or TCP/IP). Similarly, OSI-based networks employ the common management information protocol (CMIP) to transfer information regarding the operation of the network. This information is reported to a management process running on a central station which could be, for example, the main server on a given network. In essence, the management process provides a network manager with a list of all of the components on the network, e.g., routers, bridges, repeaters and the like, along with information regarding their configuration, operational status, and the like.
To facilitate the network manager's understanding of information provided by a management process, various application programs have been developed which display at least some of the information gathered by the process in a graphical format. One particularly useful type of application provides a map of the network topology. In the operation of this type of application, the network manager can view a display which illustrates all of the nodes on the network, as well as their interconnections. With this type of display, when the network manager receives information that a particular node has gone down, i.e., become non-operational, or that its performance has somehow degraded, he is able to immediately visualize the portions of the network which are affected by the drop in performance, and take appropriate corrective action. Examples of such applications include CiscoWorks Blue Logical Maps by Cisco Systems, Inc., OpenView by Hewlett Packard and NetManager by Sun Microsystems.
For networks of any appreciable size, the utility of these graphical interface programs is inversely related to the size of the networks on which they are used. For example, in a local area network or a relatively small wide area network having a few routers, the number of network components to be managed is sufficiently limited that they can all be displayed on the screen of a computer monitor, along with their interconnections, in a readily comprehensible manner. However, as the number of network components grows with the increasing size of the network, the display of all of those components becomes more complex. This complexity is due to the fact that the monitor screen becomes increasingly crowded as more icons, or the like, are added to the map to illustrate the additional network components. Furthermore, the interconnections between these components can increase exponentially, and their illustration can result in such a "busy" appearance to the screen that the information contained therein becomes incomprehensible.
It is often the case that a network manager does not need to know about the existence and state of all components in an overall network, particularly in the case of large WANs and enterprise networks. Rather, the network manager may only be responsible for a small portion of the total network, such as a few key routers and the components directly connected thereto. In such a case, the information provided by a graphical network management tool which illustrates the topology of the entire network is of little value to the network manager. It is desirable, therefore, to provide a graphical user interface for network management which permits the network manager to customize the displayed information in a manner which limits it to that which is particularly useful to the manager, and yet which provides the flexibility to navigate to any given area of the network to obtain all information necessary to properly carry out management duties.